Method of basing incandescent lamps



A. SWAN. METHOD OF BASING INCANDESCENT LAMPS.

APPLICATION FILED SEPT. 30,1918.

Patented Nov. 23, 1920.

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Inventor: Alfred Swan, /1&4. M

His ALLoT-neg.

UNITED STATES PATENT OFFICE.

ALFRED SWAN, 0F MONTCLAIR, NEW JERSEY, ASSIGNOR TO GENERAL ELECTRICCOMPANY, A CORPORATION OF NEW YORK.

METHOD OF BASIN G INGANDESCENT LAMPS.

Specification of Letters Patent. Patented N 23 1920 Original applicationfiled June 20, 1917, Serial No. 175,868. Divided and this applicationfiled September 30, 1918. Serial No. 256,351.

T 0 all toll-0m it may concern.

Be it known that I ALFRED SWAN,-L subject of the King of (irreatBritain, residing at Montclair, county of Essex, State of New Jersey,have invented certain new and use ful Improvements in Methods of BasingIncandescent Lamps, (this application being a division of my priorapplication Serial No. 175,868, filed June 20, 1917,) of which thefollowing is a specification.

My invention relates to providing incandescent lamps and similarevacuated glass vessels with metal bases cemented to the glass bulb andsoldered to leading-in wires which conduct current to the interior ofthe vessel.

One object of my invention is to improve and cheapen the basing ofincandescent lamps and similar articles. A further object is to simplifyand improve the method of applying the base to the lamp and solderingthe leading-in 'wires tothe base. To these ends .I utilize the heat ofthe exhaust oven for'cementing the bases to the bulbs, and may alsoutilize it for soldering the leading-in Wires to the base. I prefer touse a cement which has the property of first softening when heated, andthen hardening permanentlyupon continuing the heating to temperaturessuch as are commonly used- 7 during the final stages of the exhaustionof incandescent lamps. I prefer to use a cement which will stand formany weeks exposed to the air without losing the properties which makeit suitable for use in basing lamps, and hence the lined bases'need notbe used immediately, so that bases may be prepared and then stored for aconsiderable period of time if desired.

The novel features of my invention are pointed out with particularity inthe appended claims but for'purposes of illustration I have shown in theaccompanying drawings one of the various forms in which my invention maybe embodied and in which Figure -l is a longitudinal section of a lampbase of the usual type lined with cement;

'Fig. 2 is a view of a lamp showing the base in section and in theposition it assumes,

when the cement softens, with pellets of sol- 'der in position to securethe leading=in wires to the base; Fig. 3 is a longitudlnal section ofone form of,an exhaust oven suitable for -practising my invention; Fig.4 is a longitudinal section of an improved form of base particularlysuitable for use in this improved method of basing lamps; and Fig. 5 isa top view of Fig. 4.

For purposes of illustration, I have shown in Fig. 1 a lamp base of theusual type comprising a tubular threaded shell 1 havingat one end aslightly countersunk perforation 2 and closed at that end by a glass Web3 which carries a center contact 4 with a sli htly countersunkperforation. In accor ance with my invention, I apply to the inner edgeof this base a layer of cement 5. The base lined with cement is appliedto the lamp, with the leading-in wires 6,"as shown in Fig. 2, threadedthrough the perforations in the shell 1 and the center contact 4. Solderwhich will melt at the temperature attained in the exhaust oven duringexhaust, and which is preferably in the form of pellets 7, is placed inthe perforations in juxtaposition to the leading-in Wires, so that whenthe solder melts it settles into the countersunk perforations in thebase and solders the leading-in Wires to the contacts.

The lamp with the base and the leading-in Wires arran ed as shown inFig. 2 is exhausted in t e usual way. During exhaust the lamp must beheated to a high temperature to obtain a ood vacuum, and I utilize thisunavoidable eating to cement the base to the bulb, and may also use itto solder the leading-in wires to the base, thereby securing a markedsaving in time, labor and machinery. Any suitable form of exhaust ovenmay be used, such as that illustrated in Fig. 3, in which a removablecover 8 can be raised to permit the operator to insert the exhaust tubeof a lamp intoa pump connection 9 which grips the exhaust tube and holdsthe lamp in the vertical position as shown, with the base on the upperend. To prevent tarnis ing of the bases and also to settle the basessquarely upon the bulbs, I provide metal base shields 10 in the form ofloosely mounted cups which fit over the bases and which can movedownward as the cement 5 softens and press the bases firmly into'trueposition on the lamp.

After the lamps" are connected to the pump and are in position the cover8 of the exhaust oven is lowered, the lamps exers 12. As the temperatureof the oven rises, the cement softens, the bases settle down snugly onthe bulbs, and the solder melts, so that by the time the lamps areexhausted the bases are cemented in position, and the leading-in wiresare soldered to thebase. Other forms of exhaust ovens and apparatus may,of course, be used and the particular form shown is merely illustrative.

A suitable cement which I prefer to use in accordance with my inventionmay be made with materials having the properties of the condensationproduct of phenol and formaldehyde obtainable on the market under thename of bakelite. This material will dissolve in various volatilesolvents, has has the property of becoming soft and sticky at about 200(3., and at about 3009 C. is permanently converted into a hard infusiblecompound. As. this material shrinks considerably in hardening it maycrack the glass and to prevent this I mix it with an inert filler, suchas marble flour or similar powdered material. For example, I may use onepart of bakelite, from one to two parts of rosin, and from 8 to 10 partsof marble dust or similar inert filler, with sufficient solvent, such aswood alcoliol, to render the cement plastic and easily handled. Theproportions above given are by weight and preferably the dry materialsare weighed,

thoroughly mixed, and then the solvent is added.

The novel form of base shownin Figs. 4 and 5 is particularly suitablefor use with my invention. This base comprises a tubular shell 1 of theusual form, and a molded web 13, which may be made -of bakelite or somesimilar material permanently hardened by heating, before being placed inposition in the shell 1, but is preferably made of glass or refractorymaterial, particularly when the temperature of the exhaust oven is high,as at about 100 C. the finish on a bakelite web is injured. This webcarries an annular contact 14, a perforated center contact 15, and aring of cement 16 for securing it to the. shell. These webs can bemolded very quickly and cheaply with the contacts 14 and 15 in place inthem. The base with the ring 5 of cement in itis assembled by slippingthe web 13 into place in the shell 1, the assembled base placed on thelamp with the leading-in wires threaded through it, and the lamp isexhausted as previously described. The heat of the exhaust oven causesthe cement 16 on the web 13 to harden and firmly cement the web to theshell 1, while at the same time the cement 5 firmly cements the shell tothe glass of the lamp. In this way the operation of fastening the webinto the shell and base to the lamp are performed simultaneously.

What I claim as new'and desire to secure by Letters Patent of the UnitedStates, is

1. The method of exhausting a bulb and simultaneously cementing a metalmember to the bulb which consists in applying to the juxtaposed surfacesof said member and said bulb a cement which softens and becomes adhesiveat a temperature between room temperature and the temperature at whichglass softens. exhausting said bulb, and heating said bulb and memberduring exhaust to a temperature sufficient to soften said cement.

2. The method of simultaneously basing and exhausting a bulb whichconsists in exhausting the bulb, heating the bulb during exhaust, andcementing the base to the bulb during exhaust by means of a layer ofcement which is interposed between the base and bulb and which softensand becomes adhesive at the temperature attained by the bulb and baseduring exhaust.

The method of basing a bulb which consists in connecting the bulb to anexhaust pump, applying to the bulb a base provided on its inner wallswith a layer of cement which softens at about 200 C. and permanentlyhardens at about 300 C., and raising the temperature during exhaust fromroom temperature to above 300 C.-

and thereby softening and then setting said cement.

4. The method of exhausting and basing an evacuated bulb which consistsin connecting the bulb to an exhaust pump, applying to the bulb a basehaving an inner layer of a cement comprising a partial condensationproduct of phenol and formaldehyde capable of being transformed by heatinto a hard infusible form and having a filler to render the shrinkageof said cement substantially the same as that of the glass, and heatingsaid bulb during exhaust to a temperature at which said cement sets bytransformation of said product into the hard infusible form.

5. Means for exhausting and basing a bulb comprising an exhaustconnection for holding the bulb and connecting the exhaust tube of thebulb to an exhaust pump, a support normally opposite said connectionduring exhaust, and a metal cap shaped to fit overtlie base of the lampand mounted in said support to move freely toward said connection topress the base down upon the bulb.

6. An exhaust oven for incandenccnt lamps comprising an exhaustconnection to the exhaust pump adapted to hold the lamp in the oven in avertical position with the base up, means for heating the oven, and atubular shield for fitting over the base and mounted in said ovendirectly above said connection to move vertically with the base.

In witness whereof I have hereunto set my hand this 23d day of Setember, 1918.

ALF ED SWAN.

